feat: add supports_flip/flip_axis to SubPattern for Phase B flip gate

tests/unit/test_sub_pattern_flip.py

@@ -0,0 +1,33 @@
+"""SubPattern.supports_flip/flip_axis 默认值 + AR 两个子模式的翻转声明。"""
+
+from app.question_gen.strategy import SubPattern
+from app.question_gen.strategy_action_recognition import AR_SUB_PATTERNS
+
+_FLIP_EXPECTED = {
+    "temporal_reasoning_failure": "before/after",
+    "cross_segment_entity_tracking": "first/last",
+}
+
+
+def test_sub_pattern_defaults_no_flip():
+    sp = SubPattern(
+        name="x", weight=1.0, sampling_level_override=None,
+        constraint_override=None, instruction="i",
+    )
+    assert sp.supports_flip is False
+    assert sp.flip_axis is None
+
+
+def test_ar_flip_declarations():
+    by_name = {sp.name: sp for sp in AR_SUB_PATTERNS}
+    for name, axis in _FLIP_EXPECTED.items():
+        assert by_name[name].supports_flip is True, name
+        assert by_name[name].flip_axis == axis, name
+
+
+def test_other_ar_sub_patterns_keep_defaults():
+    for sp in AR_SUB_PATTERNS:
+        if sp.name in _FLIP_EXPECTED:
+            continue
+        assert sp.supports_flip is False, sp.name
+        assert sp.flip_axis is None, sp.name